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  1. #1

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    Several weeks ago I conducted tests on grades two and three Azo printing a Stouffer 21 step tablet and reading the resulting reflection densities using a 310 Xrite TR densitometer. The tests indicated that grade two Azo has a density range of 1.60 and that grade three Azo has a density range of 1.10.

    I then conducted tests on FP4 (PhotoWarehouse ISO 125 film) using Pyrocat HD 2-2-100 to arrive at development times that would provide a negative of that density range. I did this by once again exposing a Stouffer 21 step tablet and the resulting transmission densities were read using the blue channel of the same densitometer.

    My times for net negative density of 1.60 are as follows:

    N-2 Development (9 Zones contracted to 1.60) -- 6 minutes: 15 seconds
    N-1 Development (8 Zones contracted to 1.60) -- 7 minutes: 45 seconds
    N Development (7 Zones to 1.60) 11 minutes: 45 seconds
    N+1 Development (6 Zones to 1.60) 16 minutes: 45 seconds
    N+1 1/2 Development (5.5 zones to 1.60) 27 minutes: 30 seconds

    Development temperatures were 70 degrees. Film was exposed at EI 125 using incident metering. I have found that my corresponding reflective meter readings using a Zone VI modified Pentax digital meter were EI 64. The negatives were brush developed in trays.

    I have just finished printing 6 negatives that had been developed with varying contrast ranges (N to N+2) and they have printed with greater ease then what I had accomplished by relying solely on DBI.

    These results were accomplished using my equipment in my system and your results may vary.

  2. #2

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    Donald,

    For clarification, papers have exposure scales (ES), not density range. In practice what we want to do is match the DR of a negtive to the ES of the paper.

    I am surprised how close your times for FP4+ with brush develoment are to my times with rotary processing for the same DR. For example, using the SBR method, when shooting for a DR of 1.6 I need the following times wiht the 2;2:100 dilution oif Pyrocat-HD at 70F.

    SBR 10 5:00 minutes
    SBR 9 6:30 minutes
    SBR 8 9:15 minutes
    SBR 7 11:00 minutes
    SBR 6 14:00 minutes
    SBR 5 19:00 minutes

    These are the times I use with FP4+ for kallitype and palladium negatives. I am really surprised that you need a negative with this much density range for AZ0. I wonder if this isthe experience of other AZO printers?

    Sandy

  3. #3

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    Sandy,

    Thank you for informing me of the correct terminology for the paper. It makes it much easier when everyone is speaking in the same terms.

    As you will recall I exposed a Stouffer tablet on both the grade two and grade three Azo papers. I sent you the densities and corresponding steps and on the total of 1.87 range (grade two) you indicated that your program indicated a 1.60 density range for the negative. This corresponded to my trial and error early attempts (I had found that the grade two Azo would print above 1.54 from a negative that I had). Grade three Azo showed a total of 1.35. I would imagine that this would place the desired negative density range in the area of 1.10.

    After the testing with the step tablets I then shot film to determine if my actual results matched my darkroom testing. For all practical purposes the densities of my camera negatives were in line with my step tablet exposures and development times (so long as my metering was consistant).

    This afternoon I printed those negatives and the density range of the negatives matched both grade two and grade three paper very nicely. In fact these are the best Azo prints that I have been able to produce to this point.

    While I can't speak to other's experiences, I am comfortable that the paper characteristics (as tested) are consistant with what my actual experience in producing prints.

    As an aside another photographer on the Azo forum had indicated a 1.48 density range in his testing. I am not sure that he did reflection testing of the paper to determine that value though.

  4. #4

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    Donald,

    As a point of information, were your negative readings with the X-Rite 361 made with the Visual, Ortho(Blue), or UV channel?

    Sandy

  5. #5

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    Sandy,
    I read the densities with the blue channel on my Xrite 310. That model does not incorporate a UV channel.

    Additionally, In the Technical Gallery I have posted two of the images that I printed this afternoon. The grade three print has a negative DR of 1.12 and the grade two print has a DR of 1.64. I realize that images presented in this manner are inadequate but perhaps these will give some indication.

  6. #6

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    Sandy,

    Have you made tests for SBR > 10 (e.g. 11, 13, 15)? Which dilution would you be using in such cases in order that development times would not be ineffectively low? BTW, would the same apply to gentle agitation using BTZS tubes?

  7. #7

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    Francesco,

    For SBR of more than 10 I would recommend the 1:1:100 dilution of Pyrocat-HD. Develoment times for high SBR values would be too short in my opinion for the 2:2:100 dilution.

    I have test data up to SBR of 13, with DR of 1.6, for Pyrocat 1:1:100 with Ilford FP4+. BTW, amy testing method is based on the standard of gentle agitation in BTZS types tubes. Here is the information.

    SBR 13 3:00
    SBR 12 4:15
    SBR 11 5:30
    SBR 10 6:30
    SBR 9 8:00
    SBR 8 10:00
    SBR 7 15:15
    SBR 6.5 20:00

    For this high a DR (1.6) I don't recommend the use of the 1:1:100 dilution for SBR values of less than 7 (or for any N- development).

  8. #8

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    Donald,

    To avoid any misundersteanding the SBR/time values I gave for both the 2;2:100 and 1:1:100 dilution of Procat-HD were based on UV readings, not blue channel. That is because I am testing for kallitype and palladium printing which are sensitive primarily to UV light.

    In general I would need to substract about log 0.30 from my UV reading to approximate the blue reading. So in effect if your readings are giving you a density range of 1.6 with the blue channel reading this would be an effective DR of 1.9 or more for me with a UV reading. Did you check the results with your X-Rite 361 in UV mode?

  9. #9
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    Slightly off topic, but how do you use a step wedge in testing a negative? I have used mine for paper, but don't know to accurately expose film through it.

  10. #10

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    Thanks Sandy. I have ordered the kit from PFormulary and I will be receiving it very soon. The film I will be using is Efke PL100 8x10. I have exposed some negatives that had a low EV of 9 to a hi EV of 17 and 18. I will let you know how it goes.

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